Apparatus for rolling rings

ABSTRACT

This invention relates to rolling of annular workpieces by means of apparatus comprising a pressure roller, a mandrel which squeezes the workpiece against the pressure roller and backing rollers on which the mandrel rolls in line contact. Either the backing rollers or the pressure roller can be formed in two parts which can be adjusted towards and away from each other, either before or during rolling.

United States Patent Marcovitch 1 Aug. 8, 1972 [541 APPARATUS FORROLLING RINGS [72] Inventor: Jacob Marcovitch, Johannesburg,

Republic of South Africa Assignee: Rotary Profile Anstalt, Vaduz,

Liechtenstein Filed: Dec. 1, 1969 Appl. No.: 881,114

Related US. Application Data Continuation-impart of Ser. No. 605,060,Dec. 27, 1966, abandoned.

[30] Foreign Application Priority Data Jan. 4, 1966 Republic of South Jan. 10, 1966 Republic of South Africa ..66/ 105 Jan. 14,1966 Republic ofSouth Africa .66/ 226 Feb. 7, 1966 Republic of South Africa ..66/ 684Republic of South Africa ..66/261 1 Republic of South Africa ..66/865Republic of South Africa ..66/225 Republic of South Africa ..66/477 May5, 1966 Feb. 16,1966

Jan. 14, 1966 Jan. 27, 1966 Africa 66/43 April 12, 1966 Republic ofSouth Primary Examiner-Milton S. Mehr Attorney-Young & Thompson ABSTRACTThis invention relates to rolling of annular workpieces by means ofapparatus comprising a pressure roller, a mandrel which squeezes theworkpiece against the pressure roller and backing rollers on which themandrel rolls in line contact. Either the backing rollers or thepressure roller can be formed in two parts which can be adjusted towardsand away from each other, either before or during rolling.

11 Claims, 24 Drawing Figures memsnws 1912 3,681,962

SHEET 2 OF 7 Avwavrae (/6606 MmecaV/raw ,e r W PATENTEDAus 8 m23.681.962

sum 1 or 7 $4005 MAECOV/ 70H APPARATUS FOR ROLLING RINGS Thisapplication is a continuation-in-part of my copending US. Pat.application No. 605,060 filed Dec. 27, 1966 now abandoned.

This invention relates to the rolling of workpieces.

In my said co-pending application I have described the methods ofrolling annular workpieces in which the axial width of the workpieces iscontrolled by means of grooves in a mandrel or a back-up member.

It is also known to roll rings using control rings into which the metalof the workpiece is forced. However, known methods of rolling in thisway are not versatile and do not provide sufficient flexibility ofoperation, and suffer from a number of disadvantages which result mainlyfrom the inability to apply sufficient pressure to the workpiece duringrolling.

In both the methods as described in my said co-pending application andin the known art it is necessary to have special parts made i.e. eitherspecial mandrels or pressure rollers or alternatively a special controlring. While this may prove to be a satisfactory way of proceeding wherelarge numbers of rings are to be rolled, it is not satisfactory whensmall batch production, i.e. of the order of, say, 20 rings, are beingproduced. When such small numbers of rings are being produced it hashitherto been necessary, according to my knowledge, to prepare theserings by forging.

It is an object of the invention to provide an effective and yetflexible means of rolling rings with the internal or the externaldiameter of the ring and the axial width accurately sized or wallthickness and axial width of the ring accurately sized.

Another object of the invention is to control the axial spread of theworkpiece during rolling with good part definition independently ofdiametral spread. A further object of the invention is to provideapparatus for rolling rings of large diameter.

It is still a further object of the invention to provide apparatus forrolling rings of very large diameter and/or solid workpieces where veryhigh pressures are to be applied to the workpiece.

SHORT DESCRIPTION OF DRAWINGS In the drawings:

FIG. 1 shows an arrangement of the invention using the two-roller systemthe section being taken on line 1-1 of FIG. 5,

FIG. 2 shows a modified arrangement of the invention using thetwo-roller system,

FIG. 3 is a section similar to FIG. 1 of a modified arrangement of theinvention using the three-roller system,

FIG. 4 is a view of an arrangement of the invention shown in section,the section being taken on line 44 of FIG. 1

FIG. 5 is a similar section to other two-roller systems of theinvention,

FIG. 6 is a section on line 6-6 of FIG. 5,

FIG. 7 is a section similar to FIG. 5 of another embodiment,

FIG. 8 shows a modified arrangement for rolling rings of large diameter,

FIG. 9 is a section similar to FIG. 4 of a further rolling system of theinvention,

FIG. 10 is a similar view of a further embodiment,

FIGS. 11 and 12 are respectively a section and aside elevation of afurther embodiment,

FIG. 13 is a'view similar to FIG. 12 of a further embodiment,

FIG. 14 is a cross-sectional view 'of a diametral cut through an annularworkpiece, showing deformation of the workpiece under certain rollingconditions without side entrapment.

FIG. 15 is a similar view through a workpiece, showing a desired orpreferred shape of the workpiece under ideal rolling conditions or withthe embodiments of FIGS. 4 to 9 above.

FIG. 16 is a similar view through a workpiece, showing deformation undercertain conditions which it is possible to achieve with the apparatusillustrated in FIGS. 17 to 24 below.

FIG. 17 is a semi-schematic end view of a further type of apparatusaccording to the invention for rolling an annular workpiece, shown atthe start of rolling,

FIG. 18 is a partly sectioned side view of the apparatus of FIG. '17,certain parts being omitted for the sake of clarity,

FIG. 19 is a view similar to FIG. 17 of the same apparatus, near the endof rolling,

FIG. 20 is a view similar to that of FIG. 18, near the end of rollingand after re-positioning of the backing rollers,

FIG. 21 is a fragmentary side view of side rolling structure of themachine of FIGS. 17 to 20, the side rollers truing the ends of theworkpiece,

FIG. 22 is a semi-schematic view of yet another embodiment in whichthere are double backing rollers,

FIG. 23 is a semi-schematic end view of yet a further embodiment,specifically for the manufacture of lorry wheels, with a hollow rolleracting as a pressure body on the outer surface of the workpiece, and

FIG. 24 is a partly sectioned side view of the machine of FIG. 23.

GENERAL Referring now to the drawings, this invention is applicable tothe two-roller system as shown in FIG. 1 or FIG. 2 or a three-rollersystem as shown in FIG. 3.

FIGS. 4 to 6 are described as if they are two-roller systems of the kindshown in FIG. 1, but it will be apparent that these arrangements canquite easily be modified so that they are equivalent to the two-rollersystem of FIG. 2 or the three-roller system of FIG. 3. Similarly theembodiments of FIGS. 7 and 8 are described as being two-roller systemsas shown in FIG. 1 but with modifications which are obvious to thoseskilled in the art. These could be the two-roller" system of FIG. 2 orthe three-roller system of FIG. 3.

FIG. 1.

FIG. 1 shows a two-roller system. By the term two-roller system asherein used is meant a system in which an annular workpiece 10 is rolledthrough the nip between pressure means in the form of a large convexpressure roller 12 and a mandrel 14, which mandrel is backed-up byback-up roller means 16. The back-up roller means 16 in the embodimentsof the invention described with reference to FIGS. 4 to 6 comprise twoaxially aligned rollers as will be described in detail with reference tosuch figures. It will be seen that by provid ing the enlarged back-upmeans 12, large forces can be metal passing through the nip between thepressure roller 12 and the mandrel 14.

The rolling takes place by driving either the main pressure roller 12,which is the preferred arrangement, or the back-up means 16.

It will be seen that rolling of the workpiece takes place as theworkpiece l and .the mandrel 14 passes between the'nip or the closestpoints of the pressure roller 12 and the backing means 16.

FIG. 2

The two-roller system of FIG. 2 is generally similar to that of FIG. 1.In this system again a workpiece is rolled between or through the nipbetween pressure means and a mandrel 14. The mandrel again beingbacked-up by back-up means 16. The parts 10, 14 and 16 of the FIG. 2embodiment are substantially identical to the parts 10, 14 and 16 of theFIG. 1 embodiment. However, the pressure means in the FIG. 2 embodimentis the concave inner surface of an annular pressure roller 18. Becausethe workpiece 10 bears against the inner surface of the annular roller18, there will be a larger area of contact between the outer surface ofthe workpiece 10 and the innersurface of the roller 18 than exists inthe FIG. 1 arrangement where the pressure roller 12 is convex.

The same order of pressures can be applied with this arrangement andindeed perhaps slightly heavier pressures because of this larger supportarea of the pressure roller 18. v

It will also be noted that as the throat between the back-up means 16and the annular pressure roller 18 is longer as compared to the systemof FIG. 1, the workpiece 10 will be subjected to greater rollingreduction as it, the workpiece 10, and the mandrel 14 pass through thisthroat.

FIG. 3

FIG. 3 shows a three-roller system. Such a threeroller system comprisesa convex main pressure roller 12, similar to pressure roller 12 of FIG.1, and a mandrel 20 between the nip between which passes an annularworkpiece 10. The mandrel 20 is substantially the same as the mandrel 14of the FIGS. 1 and 2 embodiments save that it is provided a workingportion 22 of a reduced diameter and two heads 24 at either end of thisreduced portion. These heads 24 roll on a pair of backup means 26 and28. Each of the back-up means may comprise a pair of back-up rollerssimilar to those described with reference to FIGS. 4 to 6. The mainpressure roller 12 will be rotated or alternatively the backing rollermeans 26 and 28 may be rotated. It will be seen that with thethree-roller system, as opposed to the two-roller system, the mandrel 20can be held in position and rolling can take place as long as isdesired. The mandrel can be a plain mandrel.

FIG. 4

In FIG. 4 the back-up means 16 is comprised by a pair of cylindricalrollers 30 and 32. These rollers 30 and 32 are co-axially arranged andhave flat facing surfaces 34 and 36. The corners of which are radiusedto prevent the edges of these surfaces 34 and 36 respecworkpiece passesbetween these two surfaces. The rollers 30 and 32 may be located at anydesired distance apart to determine the axial width of the workpiece.

The rollers 30 and 32 are movable toward and away from each other tovary this axial dimention of the workpiece 10. This movement which canbe efiected by means of jacks as described with reference to FIG. 7,normally takes place before rolling commences. In this way the apparatusmay easily be used for rolling small number of rings. The movement ofthe rollers 30 and 32 axially inwardly and outwardly can also take placeduring the rolling operation. In this way better control of the metalflow during the rolling operation can take place.

It will also be noted that the rings will be rolled with substantiallysquare sides. This means that an improved workpiece is provided.

It will also be noted that due to the difference in speeds between thefaces 34 and 36 of the rollers 30 these sides will be burnished by thefaces 34 and 36.

FIGS.5AND6 In the embodiments of FIGS. 5 and 6 back-up rollers 38 and 40are generally frusto-conical in shape and are provided with conicalfaces 42 and 44 which are arranged so that the parts of the cone whichare adjacent to the mandrel 14 are perpendicular thereto at thenarrowest portion between these two faces 42 and 44. This means thatthere will be curved faces bearing against the sides of the workpiece 10as is more clearly shown in FIG. 6. In this way the amount of bumishingis held to a minimum and also the possibilities of the faces of thebacking rollers 38 and 40 scouring the sides of the workpiece is alsokept to a minimum.

FIG. 7

The rollers 46 and 48 of the embodiment of FIG. 7 are generally similarto the frusto-conical rollers 38 and 40 of the preceding embodiment.However, the rollers 46 and 48 are provided with face members 50 and 51respectively. These face members 50 and 51 are double conical sided andare arranged in suitable recesses in the rollers. The surface members 50and 51 are arranged so that their facing surfaces are in the samerelative position as the surfaces 42 and 44 of the rollers 38 and 40 ofthe FIG. 5 embodiment. Short stub axles 54 may be provided to rotate thesurface members 50 and 51 so that they approach more closely theperipheral speed of the workpiece 10. Alternatively the axles 54 may beidlers and serve merely to centralize the surface members 50 and 51. Inview of the high pressures that are going to be applied by the surfacemembers 50 and 51 on the workpiece 10, roller, taper roller or ballbearings 56 are provided between the surface members 50 and 51 and thebases of the recesses in the rollers 46 and 48 respectively. Thisembodiment when of the three-roller system is the currently'preferredembodiment.

In FIG. 8 there is shown another apparatus of the invention. Forconvenience only half of the apparatus is shown in full, the other halfof the apparatus is merely indicated by a chain dotted line.

In this apparatus there is provided backing rollers 58 which areprovided with face members 60 that rotate relatively to the backingmembers on thrust rollers 62. The face members 60 each have a stub shaft61 which is joumalled at 63 with the roller 58 to centralize theposition of the face members 60. The stub shaft 61 passes only partiallythrough the rollers 58. The backing rollers 58 are provided with stubaxles 66 which are journalled at 68 in a right angled frame 70. Thisframe 70 is connected to a pair of hydraulic cylinders, not shown, bymeans of piston rods 72 and 74 respectively. The entire apparatus iscarried in a housing 76 having openings 78 and 80 through which thepiston rods 72 and 74 respectively pass. The housing 76 has a pair ofside cheeks 82 which serve as guide means 82 between which the innerframe 70 is slidable. The inner frame also carries a secondfrusto-conical roller 84 which has a stub-shaft 86 journalled inbearings 88 in the frame 70. This frustoconical roller 84 rolls on theoutside surface of the face member 62 on the portion thereofdiametrically opposite to the place where the roller 58 contacts themandrel 14.

In this embodiment, the side faces of the workpiece roll against thefaces of the conical member 84. Thus it will be appreciated that withthis apparatus rings of greater inside and outside diameters can berolled than is possible with the apparatus of FIGS. 4 to 7.

The backing rollers 59 are movable towards and away from the pressurerollers 12 by means of the hydraulic jack through the piston rod 74.Similarly these backing rollers are moved towards each other by thepiston rod 72 of the other hydraulic jacks.

FIG. 9

In FIG. 9 there is provided the conventional mandrel 14 with two back-uprollers 168. The pressure means is however formed by two pressurerollers 90 and 92. These rollers 90 and 92 serve to define a workpiece10A which is conveniently in the form of the inner race of a roller ortaper roller bearing. The .pressure roller 90 is mainly frusto-conical.Its inside face is also frustoconical and it is arranged so that theportion of this conical face 94 is square to the axis of the mandrel 14.A short stub 96 is provided at the end of the conical face 94. Theroller 92 is also basically frusto-conical in shape having two rims 98and 100 which define between them recesses 102 and 104 at each end ofthe rolling surface of the bearing race.

In this construction the rollers 90 and 92 determine not only the widthof the workpiece but also its profile and its thickness. The thicknessis normally determined by the frusto-conical roller 90 coming intoengagement with the mandrel 14 which thereby acts as'a stop. As theprofile of the workpiece is mainly oblique and as it has re-entrantrecesses, the roller 92 is moved inwardly relative to the roller 90during rolling. This movement is indicated by the arrow 94 and is in agenerally oblique direction, but with a component in the axial directionof the rollers. The roller is also moveable relative to the roller 92 soas to control the width of the shoulder 96A of the workpiece.

Here again the rollers 90 and 92 may be set at a predetermined spacingbefore rolling but they may be movable as described above duringrotation as described with reference to the preceding embodiments.

FIG. 10

In FIG. 10 the pressure means is comprised by two annular rollers 98 and100. A back-up shaft 102 passes freely through the rollers and serves asa common backing shaft for them. The shaft 102 has a cylindricalenlargement 104. The working surfaces 106 and 108 of the rollers 98 andand the cylindrical surface of the enlargement 104 roll on the surfaceof the workpiece squeezing it, the workpiece, against the mandrel 14 inthe same way as described above.

The position of the roller 98 is set by a shoulder 110 on the shaft 102and also by the location of the enlargement 104. The position and axialmovement of the roller 98 is set by a stop 112, the location of whichmay be adjusted but is set before each rolling operation.

The enlargement 104 may be omitted in which case the rollers 98 and 100alone will determine the profile of the workpiece.

GENERAL (AS TO THE PRECEDING FIGURES) In all the embodiments describedabove the rolling of the workpiece can be effected hot, warm or cold.The rollers which move together may do so under high pressure which maybe of the order of one hundred tons per square inch.

In a particular embodiment in which a mild steel workpiece has aninitial outside diameter of 6 in. and inner diameter of 5 in. and awidth of if; in., the ring could be rolled in a few seconds to half itswallthickness in the cold in apparatus of FIGS. 5 and 6 with the threeroller system.

All the embodiments enable one to roll rings with a high degree offinish and with square parallel sides in a single operation. It will beappreciated that with this invention a ring having two of the threedimensions mentioned above may be accurately rolled, the degree ofconsistency of the third dimension depends upon the consistency of theoriginal blanks.

It will also be understood that the rolling may be carried out in stagesif the diameter of the openingin the workpiece is very small so thatinitially one would roll with a mandrel of small diameter and as thediameter of the hole increases a larger mandrel may be used so thatgreater feeds and pressures may be applied to the workpiece. It will befurther understood that the pressure means and the mandrels in all theembodiments may be profiled so as to roll profiled rings.

The apparatus above described are particularly versatile and henceuseful for a jobbing shop in which small numbers (say 20) of accuratelyrolled rings of any one set of dimensions are rolled. The apparatus canbe for rolling greater or lesser numbers of rings.

It will be understood that if the backing rollers 16 are moved towardseach other during rolling it will normally be necessary to back off thepressure roller relative to the mandrel to allow for a growth in thewall thickness of the workpiece.

It will also be noted that in all the preceding embodi ments of theinvention the movement of the rollers (e.g. 30 and 32; 38 and 40; 90 and92 etc) relative to each other is independant of relative movementbetween the mandrel and the pressure means.

FIGS. 11 AND 12 In FIGS. 11 and 12 the pressure means comprises a roller114. There are a pair of identical backing rollers 117, 118 mounted sideby side on stub axles 120 and 122 and spaced apart to provide a gap 119between them. The axles 120 and 121 are journalled in bearings 122 inbosses'123 provided by the frame 124 of the machine on either side ofthe gap 119. An annular workpiece 125 extends within the gap 1 19 andits cavity contains a mandrel 126. The mandrel 126 projects to each sideof the workpiece 125 and is formed with heads 127 that roll on therollers 117,118. The workpiece is surrounded by a control ring 128 thatlimits its diametral spread.

If it should be necessary, back-up rollers 129 are provided which bearagainst the rollers 117, 118. The back-up rollers 123 may also bearranged in pairs spaced apart to allow very large workpieces 125 toextend through the gap 119 between them. 'It is pointed out that theprovision of back-up rollers 129 pemiits the rollers 117, 118 to beloose in the sense that they need not be confined in bearings. They can,therefore, be quickly removed and replaced.

The rollers 117, 118 may be spaced apart variably in order toaccommodate workpieces of different thicknesses.

The diameter of rings which may be profiled in the machine is limitedonly by the amount of space available around the machine.

FIG. l3

In FIG. 13, the three-roller system consists of the rollers 130, 131 and132. The mandrel 133 rolls on the rollers 131, 132 and the workpiece-134is pressed by the mandrel against the periphery of the roller 130. Therollers 131, 132 are paired and mounted on stub axles, like the rollers117, 118 of FIG. 11. The workpiece extends through the gap between thepairs of rollers 131, 132.

The rollers 131, 132 may be backed up by rollers 135, which may also bepaired to allow very large workpieces to be handled.

It is pointed out that the larger the diameter of the workpiece, and thelarger the deformation required, the longer the time in, and the greaterthe number of passes through, the throat, so that the entirecircumference of the workpiece is rolled.

FIG. 14

FIG. 14 illustrates a known condition in ring-rolling according to theprior art. It will be noticed that the workpiece 10.1 has concave ends.This situation arises from rolling the workpiece between an inner and anouter pressure body, such as a pair of rollers, (not illustrated) underweak feed conditions; that is, under conditions where the inner andouter rollers are pressed relatively lightly towards each other as theyare rotated,

to advance the workpiece circumference progressively through the spacebetween them. With such rolling, normally done hot, the workpiece tendsto expand diametrically and also axially. If the axial expansion leadsto excessive concavity at the ends of the article, the article willclearly be defective, and rolling will tend to break down before thewall thickness of the workpiece has been reduced to the maximum extentthat may be desired.

FIG. 15

In FIG. 15, the workpiece 10.2 is seen to have substantially squareends. This situation will usually be ideal if considerable thinning andaxial elongation is required. However it may be unobtainable on areproducible basis except when means are provided to define the sides ofthe workpiece as indicated in FIGS.

.4 to 9 described above.

FIG. l6

FIGS. 17TO 20 In FIGS. 17 to 20, a three-roller machine for producingplain cylindrical articles is illustrated. It

comprises basically a mandrel 14, back-up means comprising centileveredbacking rollers 16, pressure means comprising a pressure roller 12, andside rollers 218. The mandrel 14 is, in the drawings, a plain cylinder,but mandrels with profiled surfaces may also be used, with due allowancefor their individual profiles.

The ends of the mandrel 14 are supported on the backing rollers 16,which in turn are set in bearings 224 in a stout framework or otherstructure 222. The parts framework 222 on each side of the workpiece 220is relatively movable, as indicated-by the arrows 250 in FIGS. 18 and 20by means of hydraulic jacks or the like 1 (not shown). The ends of thebacking rollers 14 are, as

seen in FIG. 18, separated from each other by a space 230 into which theworkpiece 220 extends, and which is axially longer than the axial lengthof the workpiece 220. As seen in FIG. 17, the inner diameter of theworkpiece 220, at the start of the operation is too small to accommodatethe ends of the backing rollers 16 and the mandrel 14; hence separatedrollers 16 are provided to form the gap 230. In practice, it may bepreferable to provide interengaging means in the form of a spigot 232 onone of the rollers 16 to interlock with a socket 234 on an axiallyaligned backing roller at the other end of the workpiece. In this waythe rigidity of the backing for the mandrel 12 may be enhanced, allowingit to take a greater load and so improving the capacity of the machine.However the provision of these interengaging means is not alwaysessential.

The pressure roller 12, bearing on the outer surface of the workpiece220, is supported on a shaft 236 in bearings 38, the shaft 36 beingfixed in robust framework structure 240 (FIG. 18). These parts are shownto small scale in the drawings for clarity. The structure 240 is movablerelatively towards and away from the axes of the backing rollers 16 andmandrel 14, also by hydraulic jacks or the like (not shown).

The ends of the workpiece 220 are trued by a series of side rollers 218,mounted to bear on the workpiece ends at points spaced about theircircumference. The rollers 218 yield to permit axial expansion of theworkpiece while simultaneously truing its ends. As seen in FIG. 21, theymay be mounted on yokes 244 that are governed by hydraulic or otherpressure means (not shown) through arms 246.

When a blank workpiece 220 is to be loaded into the machine, theframework members 222 on each side of the machine are drawn apart asshown by the arrows 250 to withdraw the spigots 232 on the rollers 14from the sockets 234 in the opposite rollers 14. The workpiece 220 isthen threaded on to the backing rollers 16. The mandrel 14 is placed inposition, and the framework members 222 are advanced until the ends ofthe mandrel 14 are supported by the rollers 16. In this position therollers 16 do not extend into the hollow of the workpiece, except asregards the spigot 232. To complete loading of the machine and bring itto the condition shown in FIGS. 17 and 18, the pressure roller 12 isbrought into contact with the outer surface of the workpiece 220.

Rolling then begins. The pressure roller 12 is rotatably driven (by anyconventional means not illustrated) to impose rotation frictionally onthe workpiece 220, the mandrel 14, and the backing rollers 16. If needbe some of the rotary members other than the pressure roller 12 may bedriven to attain the correct conditions. This rotation advances theworkpiece circumference progressively through the nip or space betweenthe mandrel 14 and the pressure roller 12. By applying a suitable feedbetween the pressure roller 12 and the backing rollers 16, (eg by themeans which move the structure 240), the workpiece 220 is deformed underpressure to cause it to expand diametrically. Axial expansion isregulated to a required factor by the side rollers 218.

After a measure of deformation, the workpiece diameter has increased tothe point where the inner diameter clears the ends of the backingrollers 16, viewed from the end. At this stage rolling is halted. Theforce urging the pressure roller 12 towards the backing rollers 16 isslackened, now the framework members are moved in the direction of thearrows 250, so that the spigots 232 are forces fully into the sockets234 and the inner faces of the rollers 16 butt against each other tomake the rollers 16 extend effectively continuously through theworkpiece aperture. Alternatively a mandrel of larger diameter can besubstituted for the mandrel originally used. The biggest mandrelpossible should be used at each stage if one desires maximum feed andhence more working throughout the depth of the ring wall. In thiscondition, seen in FIGS. 19 and 20 the mandrel 14 is supported along itsfull length and not only at its ends. Rolling can then be resumed atvery large feed forces since with the improved backing for the mandrel14, these forces can be accommodated by the machine without unduestress. Since at this stage the workpiece 220 is thinner than before andoffers greater resistance to deformation, the gain in feed forcecapacity is extremely useful.

It is obvious that the ends of the workpiece can be constrained by theside rollers 218 throughout the operation, to prevent raggedness orirregularity at these ends, leading to the production of a well finishedarticle at the end of the operation.

The unloading procedure is simple, the pressure roller 12 beingwithdrawn and the backing rollers 16 being drawn apart to allow theworkpiece to be freed and removed from the machine with the mandrel.

.FIG. 22

FIG. 22 illustrates a development of the invention in which there aretwo pairs of backing rollers 16 to support the mandrel. As in themachine of preceding FIGS. 17 to 21, there is a pressure roller 12, amandrel 14, a series of side rollers 218, and a pair of backing rollers16 on which each end of the mandrel 14 rolls. In addition, a pair ofsecondary backing rollers 260 at each end on which the backing rollers16 in turn are supported. The structure holding these components inposition and driving the machine is not illustrated.

The workpiece 250 is shown in solid lines in its ex-. panded state andin its initial state is shown in chain lines at 250A. It is obvious thatthe workpiece 250A cannot accommodate within its aperture the mandrel l4and the double backing rollers 16 and 260. Thus the operation startswith the rollers 16 and 260 axially separated at the ends of themandrel. The rollers 16 and 20 are brought into axial abutment when theworkpiece has expanded to the diameter shown by 250. If desired, therollers 16 can be moved into abutment as soon as they can beaccommodated in the workpiece.

FIGS. 23 AND 24 Another development is shown in FIGS. 23 and 24. Herethere is again a mandrel 14B, backing rollers 16 with (if desired)spigot connections 132 and 234 (see FIG. 24), an annular workpiece 270and a pressure means. In this case pressure means comprises a hollowroller 272. The interior concave surface 274 of roller 272 bears on theouter surface of the workpiece 270. The roller 272 is set in bearings276 in framework structure 278. The mandrel 148 has a tapered end 280that, as seen in FIG. 24, provides a taper on the finished workpiece270, which in this case is a lorry wheel. Side rollers 282 roll the endzone of the workpiece 270 into a flange 284, the pressure roller 272being rebated to accommodate the flange 284.

With the machine of FIGS. 23 and 24, the workpiece 270 is initiallyinserted into the hollow of the roller 272 with the mandrel 14B threadedthrough it, and the backing rollers 16 are closed up axially to allowthe ends of the mandrel to roll on the rollers. The backing rollers 16are themselves located axially beyond the ends of the workpiece. Whenrolling has advanced sufficiently, the backing rollers 16 are broughtaxially together within the workpiece aperture to attain the situationshown in FIG. 24, so providing support for the mandrel 14B continuouslyalong its length.

required value. The finished workpiece 270 is removedfrom the roller 272by suitable ejection means (not illustrated).

A loose control ring for this purpose might be used with the machinesdescribed earlier.

In this embodiment, as in the embodiment of FIGS. 17 to 21, the rollingof the workpiece can be effected hot, cold or warm. The pressures inthis embodiment may be of the same order as in the preceding embodiment.

Iclaim:

1. In apparatus for rolling rings from annular workpieces comprisingmain pressure means and .a onepiece mandrel which in use are urgedtowards each other to squeeze a workpiece therebetween and the apparatusfurther comprising back-up means on which at least part of the mandrelrolls;.the improvement that the back-up meanscomprises at leastv one setof two rollers which are axially spaced apart and are disposed on andcontact the side of the mandrel opposite the main pressure means. I

2. The invention as claimed in claim 1 further comprising movable meansoperatively connected to at least one of the rollers to move them toadjust the axial spacing between the rollers during operation of theapparatus.

3. The invention as claimed in claim 2 in which the movement of the saidrollers is independent of the in use contacts the sides of a workpiecebeing rolled in the apparatus.

6. The improvement as claimed in claim 5 wherein the conical frontportion is rotatable relative to the said frusto-conical portion of theroller.

. 7. The invention as claimed in claim 6 further comprising axle meansattached tothe said conical front portion and passing at least partiallythrough the said frusto-conical portion of the roller.

8. The improvement as claimed in claim 5 further comprising anadditional conical roller rolling on the front portion of each rollerand in use contacting the sides of a workpiece being rolled in theapparatus.

9. The invention of claim '1 comprising slidable interengaging meansconnecting the rollers.

10. The invention as claimed in claim 9 in which the interengaging meanscomprises a stub shaft on one of the rollers and a socket in saidinterengaging means, which socket slidably receives the said stub shaft.

11. The invention as claimed in claim 1, wherein the axial spacingbetween the rollers is adjustable.

1. In apparatus for rolling rings from annular workpieces comprisingmain pressure means and a one-piece mandrel which in use are urgedtowards each other to squeeze a workpiece therebetween and the apparatusfurther comprising back-up means on which at least part of the mandrelrolls; the improvement that the back-up means comprises at least one setof two rollers which are axially spaced apart and are disposed on andcontact the side of the mandrel opposite the main pressure means.
 2. Theinvention as claimed in claim 1 further comprising movable meansoperatively connected to at least one of the rollers to move them toadjust the axial spacing between the rollers during operation of theapparatus.
 3. The invention as claimed in claim 2 in which the movementof the said rollers is independent of the movement of the pressure meanstowards the mandrel.
 4. The invention as claimed in claim 1 in which theback-up means comprises two sets of rollers on which the mandrel rolls,the axial spacing between the rollers of each set being adjustable. 5.The improvement as claimed in claim 1 in which each of the said rollershas a frusto-conical portion on which the mandrel rolls and a conicalfront portion that in use contacts the sides of a workpiece being rolledin the apparatus.
 6. The improvement as claimed in claim 5 wherein theconical front portion is rotatable relative to the said frusto-conicalportion of the roller.
 7. The invention as claimed in claim 6 furthercomprising axle means attached to the said conical front portion andpassing at least partially through the said frusto-conical portion ofthe roller.
 8. The improvement as claimed in claim 5 further comprisingan additional conical roller rolling on the front portion of each rollerand in use contacting the sides of a workpiece being rolled in theapparatus.
 9. The invention of claim 1 comprising slidable interengagingmeans connecting the rollers.
 10. The invention as claimed in claim 9 inwhich the interengaging means comprises a stub shaft on one of therollers and a socket in said interengaging means, which socket slidablyreceives the said stub shaft.
 11. The invention as claimed in claim 1,wherein the axial spacing between the rollers is adjustable.